The origin of severe acute respiratory syndrome-associated coronavirus(SARS-CoV) is still a matter of speculation, although more than oneyear has passed since the onset of the SARS outbreak. In this study, we implementeda 3-step strategy to test the intriguing hypothesis that SARS-CoVmight have been derived from a recombinant virus. First, we blasted the wholeSARS-CoV genome against a virus database to search viruses of interest. Second,we employed 7 recombination detection techniques well documented in successfullydetecting recombination events to explore the presence of recombinationin SARS-CoV genome. Finally, we conducted phylogenetic analyses to furtherexplore whether recombination has indeed occurred in the course of coronaviruseshistory predating the emergence of SARS-CoV. Surprisingly, we found that 7putative recombination regions, located in Replicase 1ab and Spike protein, existbetween SARS-CoV and other 6 coronaviruses: porcine epidemic diarrheavirus (PEDV), transmissible gastroenteritis virus (TGEV), bovine coronavirus(BCoV), human coronavirus 229E (HCoV), murine hepatitis virus (MHV), andavian infectious bronchitis virus (IBV). Thus, our analyses substantiate the presenceof recombination events in history that led to the SARS-CoV genome.Like the other coronaviruses used in the analysis, SARS-CoV is also a mosaicstructure.